Compilare: main.cpp: In function 'int main()': main.cpp:20:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | for(int i = 0;i < s.size();i++){ | ~~^~~~~~~~~~ main.cpp:21:16: warning: array subscript has type 'char' [-Wchar-subscripts] 21 | id[s[i]] = i; | ^ main.cpp:27:30: warning: array subscript has type 'char' [-Wchar-subscripts] 27 | pos[id[v[i][j]]] = {i,j}; | ~~~~~~^